There are many well known methods for applying indicia, designs, logos, and other decoration to three-dimensional surfaces. Printing indicia on a variety of three-dimensional surfaces, such as sporting goods, in particular, the dimpled surface of golf balls and other golf equipment, is often used as a means of advertising and labeling.
There are different approaches commonly used, mostly water-based or solvent-based systems, to add indicia to the dimpled surface of a golf ball. One approach involves first creating a decal of the logo or indicia that is to be printed on the golf ball surface, applying the decal to the spherical, dimpled golf ball surface of the cover, and then spraying the golf ball surface and decal with a clear finish coating. Pad printing is also often used for marking golf ball surfaces, however, very few of the inks employed in pad printing are suitable for use on a golf ball. More specifically, when applied to a golf ball, these inks are not sufficiently durable (impact resistant) to withstand multiple blows by a golf club. U.S. Pat. No. 6,179,732 discloses a method for applying markings to a golf ball during formation using a two-part mold and a mark-bearing film on the wall of the mold.
During manufacturing of golf balls using conventional printing methods, ink transfer problems are often encountered. For example, in pad printing it is desirable that all of the ink picked up by the printing pad be fully released onto the article to be printed, however, sometimes complete release is not achieved. Consequently, subsequent articles to be printed upon by the same printing pad member can have excessive ink or misaligned ink deposited thereon leading to unwanted ink contamination of balls. Resolution of such problems requires expensive positioning equipment to prevent unwanted contact between balls, between ink depositing members and balls, and between ball handling equipment and balls, respectively.
In addition to the problems associated with ink transfer before the ink is cured, post manufacturing problems are also commonly encountered even after curing takes place. The current water-based inks that work reasonably well for printing on absorbent substrates such as paper, paperboard, boxboard, and cardboard do not adhere well to the smooth, nonporous materials typically used in layers of a golf ball. To reduce adherence problems, golf balls generally are subjected to a clear coat covering the golf ball and the printed pattern after an indicia is applied in order to improve appearance as well as to protect the indicia from degradation during the golf ball's normal useful life due to normal play. There are multiple sources of possible degradation to the ball. For example, the ball may be degraded from being struck with a grooved club head or by landing on a rocky or abrasive surface such as a cart path. When adhesion between the protective clear coat and the ink layer of the printed pattern is weak, however, the ink layer can flake, crack, or otherwise degrade more easily under less harsh circumstances. After repeated impacts, such lack of adhesion, toughness, flexibility, and/or hardness yields an unsightly golf ball.
Because a clear coat is typically applied to a golf ball after printing the indicia, custom orders, e.g., imprinting a company logo for a relatively small quantity order, usually requires a special production run that tends to be expensive for the consumer.
Furthermore, water-based coatings, in general, while desirable due to the low toxicity of the solvent, are much harder to evaporate than volatile organic materials, and therefore, are energy intensive, requiring expensive drying ovens to remove the water.
Moreover, coatings and inks used in spraying and pad printing techniques typically involve volatile organic compounds (VOC) found in the compounds used. Manufacturers of printed products may be strongly affected by federal and local regulations that impose restrictions on the emission of VOCs, such as methyl ethyl ketone, acetone, toluene, alcohols, and chlorinated solvents, to the atmosphere.
The imaging of textiles and other materials using thermal transfer of sublimable dyes has been commercially practiced for more than 50 years. Sublimation transfer processes have been found to be particularly useful in printing onto polyester fabric. Excellent color quality and efficient transfer is possible with such fabrics, but poor results have previously been obtained on non-textile items such as wood, particle board, plastic sheets, leather, rubber and other organic or natural materials.
In general, sublimation printing requires a temporary support, such as a carrier or transfer sheet, having a sublimable ink and other components applied thereto. Application of the ink onto a substrate can take place by a number of well known techniques such as rotogravure, offset or flexographic printing. The temporary support is brought into contact with the substrate, generally a textile material. Application of heat and pressure cause the dispersed dyes in the ink to evaporate and migrate from the temporary support into the substrate being processed. The method is clean, fast, and without the emanation of noxious vapors and solvents. Other materials such as steel, aluminum, and composite materials such as graphite, wood, ceramic, clay, and glass, have also been successfully marked using dye sublimation, however, the melting temperatures of these substrates have all been substantially high so as to withstand the traditional high temperatures and pressures of the dye sublimation process.
The present invention provides a novel method for forming indicia on a three-dimensional surface, in particular, components of a golf ball, through dye sublimation that advantageously provides increased indicia durability and decreased VOC emission to the environment. The present invention also allows for indicia to be applied to interior surfaces of golf ball components before applying subsequent layers thereon.